The present invention relates to a transport system with inductive energy transfer from an underfloor primary conductor to a secondary conductor in an electric transport vehicle, an electric transport vehicle of such a system, and a method of guiding such a vehicle of such a transport system.
A transport system with inductive energy transfer from an underfloor primary conductor to a secondary conductor in an electric transport vehicle is known from the following patent specification and patent applications: DE 199 47 368 C1, DE 199 55 042 A1, and DE 100 13 767 A1.
The transport systems described in DE 199 47 368 C1 and DE 199 55 042 A1 comprise electric transport vehicles which are guided mechanically. These electric transport vehicles have at least three guide bolts protruding into a guide channel provided in an underfloor track system for engagement and for guidance of the transport vehicles along the track system. Such mechanical guidance has the disadvantage that the track body in which the guide channel is provided is abraded during use. Such abrasion is particularly problematic, in a case wherein heavy loads are transported by the electric transport vehicles, especially in curves of the track system. Hence, regular replacement of the track body comprising the guide channel or at least parts of the track body comprising the guide channel become necessary for operating reliably such transport systems. The replacement of a track body or of major parts of the track body leads to unwanted long down-time of the transport system, and thus to a machine down-time in the whole assembly line in which the transport system is used. Since such transport systems are used in industry, e.g. in the automobile industry, a long down-time of an assembly-line has a large impact on the production costs and thus the efficiency of the manufacture.
The transport system described in DE 100 13 767 A1 comprises electric transport vehicles which are guided optically. However, the electric transport vehicles comprise at least three sensor units for guiding the vehicle and for maintaining a pick-up unit essentially within the electromagnetic field provided by the primary conductor of the track system. Thus, a difficult and complicated control of signals of at least three sensor units is necessary.
Further, transport systems were suggested, wherein the guidance of transport vehicles and their pick-up units essentially within the electromagnetic field of a primary conductor requires a complicated system of rod guided axles, wheels, and pick-up units. Such a system is unreliable and expensive.
Hence, it is the object of the present invention to overcome the drawbacks of the transport systems according to the prior art. Particularly, it is the object of the present invention to provide an improved, inexpensive, and simplified transport system with inductive energy transfer from an underfloor primary conductor to a secondary conductor provided in a transport vehicle, whereby the transport vehicle is guided contact-less, reliably, and essentially within the electromagnetic field of the primary conductor during travel for a maximum of the energy transfer.